I have been working on the tune for my 1990 Corvette and have found that it shows a knock detection at 1600-1650 rpm. I can not seem to identify what is causing it and have tried backing off the spark table to counter it with no avail the knock retard remains at the same value. This is only at 70mph, 2mph lower or higher the spark magically disappears. I'm not sure how to combat this. Any help would be appreciated.
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